The present invention relates to a novel form of 5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)-methyl]sulfinyl]-1H-benzimidazole, known under the generic name omeprazole. More specifically, it relates to a novel crystalline form of the potassium salt of the (S)-enantiomer of 5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole. The present invention also relates to a process for preparing such a form of potassium salt of (S)-omeprazole and pharmaceutical compositions containing it.
The compound 5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole, having the generic name omeprazole, and therapeutically acceptable salts thereof, are described in EP 5129. The specific alkaline salts of omeprazole are disclosed in EP 124 495. Omeprazole is a proton pump inhibitor, i.e. effective in inhibiting gastric acid secretion, and is useful as an antiulcer agent. In a more general sense, omeprazole may be used for prevention and treatment of gastric-acid related diseases in mammals and especially in man.
Omeprazole is a sulfoxide and a chiral compound, wherein the sulfur atom is the stereogenic center. Thus, omeprazole is a racemic mixture of its two single enantiomers, the (R)- and (S)-enantiomer of omeprazole, herein referred to as (R)-omeprazole and (S)-omeprazole. The absolute configurations of the enantiomers of omeprazole have been determined by an X-ray study of an N-alkylated derivative of the (+)-enantiomer in non-salt form. The (+)-enantiomer of the non-salt form and the (xe2x88x92)-enantiomer of the non-salt form were found to have R and S configuration, respectively. The conditions for the optical rotation measurement for each of these enantiomers are described in WO 94/27988.
Certain salts of the single enantiomers of omeprazole and their preparation are disclosed in WO 94/27988. These compounds have improved pharmacokinetic and metabolic properties which will give an improved therapeutic profile such as a lower degree of interindividual variation.
WO 96/02535 discloses a process for the preparation of the single enantiomers of omeprazole and structually related compounds as well as salts thereof WO 96/01623 discloses pharmaceutical dosage forms comprising for instance magnesium salts of (R)-and (S)-omeprazole.
WO 98/54171 discloses a process for the preparation of the trihydrate of magnesium salt of (S)-omeprazole, wherein the potassium salt of (S)-omeprazole is used as an intermediate. The potassium salt of (S)-omeprazole, according to the prior art, crystallizes as a methanol solvate.
Certain salts of of (S)-omeprazole, such as the potassium salt, are in general suitable compounds for i.v.-administration due to their intrinsic properties, such as high stability and high solubility in water. Methanol solvates are however not suitable for i.v.-administration, since the concomitant administration of methanol could be fatal for the receiver. Therefore there exists a need for a potassium salt of (S)-omeprazol that is free from methanol.
The novel form of the potassium salt of (S)-omeprazole according to the present invention is hereinafter referred to as the potassium salt of (S)-omeprazole form B. The prior art form of the potassium salt of (S)-omeprazole disclosed in WO 98/54171 is hereinafter referred to as the potassium salt of (S)-omeprazole form A.